Iron Carbonyl Thiourea Hybrid Material Based on Functionalised Silica from Rice Husk Ash for Oxidation of Limonene

Iron carbonyl thiourea, RHACP1Fe was successfully immobilized onto inorganic silica support from rice husk ask via chloropropyltriethoxysilane (CPTES) and the resulting catalyst was labelled as RHACP1Fe. This mesoporous organic-inorganic hybrid catalyst showed a specific surface area of 245.0 m²g^-1. The ²⁹ Si MAS NMR solid state spectrum showed the presence of Q⁴, Q³, T³ and T² silicon centres in RHACP1Fe. The oxidation of limonene with H₂O₂ was studied using RHACP1Fe. A moderate selectivity to the desired product (limonene peroxide) of 67% and a maximum limonene conversion of 60% was achieved. RHACP1Fe could be reused several times without losing its catalytic activity.     

Adsorption of Hazardous Azorhodanine Dye from an Aqueous Solution Using Rice Straw Fly Ash

The potential of using rice straw fly ash (RSFA) as low-cost adsorbents for the removal of hazardous azorhodanine (AR) dye from aqueous solution was investigated. The effects of different variables in the batch method as a function of solution pH, contact time, concentration of adsorbate, adsorbent dosage, and temperature were investigated, and optimal experimental conditions were ascertained: 0.05 g for initial dye concentration of 20–100 mg/L at pH 2. The experimental equilibrium data were tested by the isotherm models, namely the Langmuir and Freundlich adsorption and the isotherm constants were determined. The kinetic models, pseudo-first-order and pseudo-second-order, were employed to analyze the kinetic data. The activation energy of adsorption was also evaluated and found to be +10.89 kJ.mol^?1, indicating that the adsorption is physisorption. Various thermodynamic parameters, such as Gibbs free energy, entropy, and enthalpy of the ongoing adsorption process, have been calculated and found to be spontaneous and exothermic, respectively.     

聚乙二醇-400中磺化稻壳灰催化2-取代苯并噁唑的合成

以邻氨基苯酚（1）和芳醛（2a~2i）［或脂肪醛（2j, 2k）］为原料,聚乙二醇(PEG-400)为溶剂,稻壳灰负载氯磺酸（AC）为固体酸催化剂,采用超声辅助的“一锅法”合成了11个2-取代苯并噁唑(3a~3k),其结构经¹H NMR, IR和元素分析确证。以3a和3j的合成为例,优化了反应条件。结果表明：在最优合成条件［1 1 mmol, 2 1.2 mmol, AC 10 mol%, PEG-400 5 mL,于200 W超声30 min(3a)或60 min(3j)］下,3a和3j收率分别为92.4%和82.4%。 AC重复使用5次,3a收率84.7%。 PEG-400回收率约79%。     

Synthesis,Characterization, and Catalytic Behavior of Bamboo Rice Husk Ash

In this paper, we report the use of bamboo rice husk ash as an efficient, greener, reusable, and biodegradable heterogeneous catalyst for the synthesis of tetrahydro‐4H ‐chromene‐3‐carbonitriles via the one‐pot three‐component reaction of malononitrile with aromatic aldehydes and dimedone or 1,3‐cyclohexanedione. The formation of bamboo rice husk ash‐silica has been confirmed by several analytical techniques.     

Evaluation of Properties of Concrete Without Cement Produced Using Fly Ash-Based Geopolymer

The use of ordinary Portland cement (OPC) in the construction industry is inevitable. The huge production of OPC and its use in infrastructural development pose an environmental impact. Greenhouse gas emitted increases the global temperature and it is an alarming sign to everybody on the planet. Concrete is the most consuming material which is produced by using OPC and it is proven that OPC contributes a lot to CO₂ emission. Hence in this study attempt is made to produce concrete by using environment-friendly material like fly ash along with alkaline activators, which is termed Geo polymer concrete. The by-product fly ash is widely available worldwide. It is a by-product of thermal power plants. The use of fly ash in concrete produces less expensive and more cost-effective concrete than concrete made up using OPC. Due to its high silicate and alumina content, fly ash reacts with an alkaline solution to create an aluminosilicate gel that binds the aggregate and results in high-quality concrete. Fly ash is finer than cement, it occupies the pores of cement after hydration. This would result in denser concrete which gives higher strength. In comparison to ordinary concrete, fly ash-based geopolymer concrete offers better resistance to aggressive environments and high temperatures. In the present study, an alkaline activator of molarity 8 is used to prepare geopolymer concrete. The test specimens are cast and cured for 28 days. Test results indicate that an alkaline liquid fly-ash ratio (0.4) produces higher mechanical properties. Hence, geopolymer concrete produced in this study is found to be cost-effective and environment friendly.     

粉煤灰理化性质及改土增产效应研究

研究了粉煤灰的理化性质及改土增产效应。结果表明，粉煤灰颗粒以物理性砂粒为主，含有Ｓｉ、Ｆｅ、Ｐ、Ｋ、Ｃａ、Ｍｇ、Ｚｎ、Ｃｕ、Ｍｏ、Ｂ等作物营养元素；施用粉煤灰能提高土壤物理性砂粒含量，增加土壤孔隙度，降低容量，对粘重土壤具有良好的改土效应。     

Separation of Pt(IV) from Industrial Wastewater Using Rice Husk Adsorbent and Its Derivatives

Some novel adsorbents were prepared by rice husk (RH). The esterified rice husk (RHS) was prepared by treating RH with anhydride of succinic acid to introduce carboxylic function to rice husk. This RHS was used to anchor various polyamines, viz., ethylenediamine (ED) and diethylenetriamine (DT) to prepare new adsorbents. These adsorbents were used to separate Pt(IV) from synthetic as well as industrial wastewaters. Adsorbents were characterized by Fourier transform infrared spectra, elemental analysis, scanning electron microscopy, and energy dispersive x-ray spectrometry. The selectivity order for Pt(IV) removal found was: RHS-DT > RHS-ED > RH > RHS. The Freundlich isotherm provided the high correlation (0.9750–0.9938) for the adsorption with low SSE (0.00215–0.00785) value of Pt(IV) for all the adsorbents. Among the kinetic models, pseudo-second order kinetic model was found to best fit with high correlation for all the adsorbents. The results of thermodynamic parameters suggest that the Pt(IV) adsorption was spontaneous and endothermic in nature. The maximum percentage of desorption of Pt(IV) metal ion was obtained when the reagent HCl–thiourea mixture was used as desorbing agent.     

Surface Modification of Rice Husk Ash by Ethanol-assisted Milling to Reinforce the Properties of Natural Rubber/Butadiene Rubber Composites

Rice husk ash(RHA), obtained by pyrolysis of rice husks, can be used as a potential reinforcing filler for rubber composites. In this work, ball milling in ethanol(ethanol-assisted milling) was used to hydroxylate the surface of RHA, promoting the graft modification of bis-(γ-triethoxysilylpropyl)-tetrasulfide(Si69). The obtained modified RHA(RHA-EM-Si69) was filled into the natural rubber/butadiene rubber(NR/BR) composites, and the filler-rubber interactions were enhanced. In consequence, RHA-EM-Si69 filled NR/BR composites showed overall improvement in the mechanical properties compared with RHA filled NR/BR composites. The tear strength increased from 13.37 kN/m to 34.71 kN/m, and the tensile strength increased from 1.84 MPa to 7.75 MPa. Carbon black(N774) was also used for comparison under the same conditions. This method provides a potential for promoting the value of RHA in rubber industry.     

Effect of Atmospheres on Transformation of Heavy Metals during Thermal Treatment of MSWI Fly Ash: By Thermodynamic Equilibrium Calculation

The vaporization behaviors of eight heavy metals (Pb, Zn, Cu, Cd, Cr, Co, Mn, and Ni) in municipal solid wastes incineration (MSWI) fly ash during thermal treatment under air atmosphere (21% O₂/79% N₂), an inert atmosphere (100% N₂), and a reducing atmosphere (50% CO/50% N₂) were evaluated based on a thermodynamic equilibrium calculation by FactSage 8.1. The results show that the reducing atmosphere promotes the melting of MSWI fly ash, resulting in a more liquid phase than in air or an inert atmosphere. Except for Cd, the formation of liquids can dissolve heavy metals and reduce their vaporization ratio. In the air and inert atmospheres, Pb, Zn, Cu, Co, Mn, and Ni vaporize mainly in the form of metallic chlorides, while Cd volatilizes in the form of metallic Cd (g) and CdO (g). In the reducing atmosphere, Co, Mn, and Ni still vaporize as chlorides. Zn and Cd mainly vaporize in the form of Zn (g) and Cd (g), respectively. In terms of Pb, in addition to its chlorides, the volatiles of Pb contain some Pb (g) and PbS (g). Cr has a low vaporization ratio, accounting for 2.4% of the air atmosphere. Cr, on the other hand, readily reacts with Ca to form water-soluble CrCaO₄, potentially increasing Cr leaching. Except for Cd, the results of this study suggest that the reducing atmosphere is used for the thermal treatment of MSWI fly ash because it promotes the melting of fly ash and thus prevents heavy metal vaporization.     

C/粉煤灰复合吸附材料的制备及表征

以粉煤灰和蔗糖为原料,浓硫酸为炭化剂,制备了一种新型的C/粉煤灰复合吸附材料。 采用X光电子能谱、红外吸收光谱、场发射扫描电子显微镜、X射线衍射及N2气吸附实验对所制备复合材料进行了表征。 结果表明,粉煤灰表面被类石墨态炭纳米颗粒所包裹,复合材料表面密集分布着大量的介孔,Brunauer-Emmett-Teller(BET)比表面积SBET=5.4 m2/g,并且在该复合材料表面含有丰富的-SO3H、-COOH和-OH等含氧官能团。 考察了所制备的复合材料对典型阳离子型染料亚甲基蓝及重金属离子的吸附能力,结果表明,该复合材料具有优异的吸附性能,其对亚甲基蓝的吸附能力达到活性炭的83.7%,对典型重金属离子的吸附能力优于市售活性炭。 所制备复合材料可作为活性炭的一种替代品,用于水中有机染料和重金属离子的吸附处理。     

稻壳纤维素强酸性阳离子交换剂

交换容量;重金属离子;稻壳纤维素强酸性阳离子交换剂     

Characterization of Bio-Fuel and Bio-Fuel Ash

Three bio-fuels with or without additives and their fly ash samples were characterized using simultaneous Thermogravimetry-Differential Thermal Analysis-Fourier Transform Infrared Spectrometry-Mass Spectrometry (TG-DTA-FTIR-MS), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscopy-Energy Dispersive Spectrometry (SEM-EDS). The results show that the additives increase the reactivity of the bio-fuel during combustion. The additives also significantly decrease the amount of unburned carbon in the fly ash. The additives affect the compounds formed in the fly ash sample, and consequently the thermal behaviour of the fly ash. The fly ash samples are thermally stable in air up to 100°C. The fly ash samples contain fine particles with irregular shape, small round particles, and large hollow spherical particles with entrapped gases. This revised version was published online in July 2006 with corrections to the Cover Date.     

石墨探针原子化法测定土壤和煤飞灰中的钴

用试验优化设计研究了测定钴的条件,考察了某些元素对测定钴的干扰效应,建立了土壤和煤飞灰中钴的测定方法。     

Rice Husk Ash: A New,Cheap, Efficient,and Reusable Reagent for the Protection of Alcohols,Phenols, Amines,and Thiols

Abstract

A mild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text, tables, and figures.]     

Inhibitory Effect of Thai Purple Rice Husk Extract on Chemically Induced Carcinogenesis in Rats

This study investigated the cancer chemopreventive effects of an acidic methanol extract of purple rice husk on chemically induced carcinogenesis in rats. This purple rice husk extract (PRHE) had high polyphenol contents. Vanillic acid was a major phenolic compound in PRHE. Three major anthocyanins found in PRHE were malvidin-3-glucoside, peonidin-3-glucoside and cyanidin-3-glucoside. PRHE was not toxic and clastogenic in rats. The LD₅₀ of PRHE was greater than 2000 mg kg⁻¹ body weight (BW). The oral administration of 300 or 1000 mg kg⁻¹ BW of PRHE for 28 days significantly decreased the number of micronucleated hepatocytes in diethylnitrosamine-initiated rats. The inhibitory mechanisms were associated with the reduction of cytochrome P450 2E1 expression and induction of some detoxifying enzymes in the liver. In addition, treatment with 500 mg kg⁻¹ BW of PRHE for eight weeks did not induce preneoplastic lesions in the liver and colon. It significantly inhibited hepatic glutathione-S-transferase positive foci formation induced by diethylnitrosamine and 1,2-dimethylhydrazine by suppression of hepatocyte proliferation and induction of apoptosis. In conclusion, PRHE did not present toxicity, clastogenicity or carcinogenicity in rats. It exhibited cancer chemopreventive properties against chemically induced early stages rat hepatocarcinogenesis. Anthocyanins and vanillic acid might be candidate anticarcinogenic compounds in purple rice husk.     

原子荧光光谱法快速测定粉煤灰中砷与汞

采用王水分解试样-原子荧光光谱法(AFS)测定粉煤灰中的砷、汞,方法回收率分别为98.5%~102.0%、85.0%~105.0%,相对偏差分别为1.9%~4.8%、0.6%~2.4%.方法具有快速、简便、灵敏等优点,对探讨粉煤灰在农业生态环境方面的综合利用颇有价值.     

Alkali-Activated Hybrid Cements Based on Fly Ash and Construction and Demolition Wastes Using Sodium Sulfate and Sodium Carbonate

This article demonstrates the possibility of producing alkali-activated hybrid cements based on fly ash (FA), and construction and demolition wastes (concrete waste, COW; ceramic waste, CEW; and masonry waste, MAW) using sodium sulfate (Na₂SO₄) (2–6%) and sodium carbonate (Na₂CO₃) (5–10%) as activators. From a mixture of COW, CEW, and MAW in equal proportions (33.33%), a new precursor called CDW was generated. The precursors were mixed with ordinary Portland cement (OPC) (10–30%). Curing of the materials was performed at room temperature (25 °C). The hybrid cements activated with Na₂SO₄ reached compressive strengths of up to 31 MPa at 28 days of curing, and the hybrid cements activated with Na₂CO₃ yielded compressive strengths of up to 22 MPa. Based on their mechanical performance, the optimal mixtures were selected: FA/30OPC-4%Na₂SO₄, CDW/30OPC-4%Na₂SO₄, FA/30OPC-10%Na₂CO₃, and CDW/30OPC-10%Na₂CO₃. At prolonged ages (180 days), these mixtures reached compressive strength values similar to those reported for pastes based on 100% OPC. A notable advantage is the reduction of the heat of the reaction, which can be reduced by up to 10 times relative to that reported for the hydration of Portland cement. These results show the feasibility of manufacturing alkaline-activated hybrid cements using alternative activators with a lower environmental impact.